| Goaf in coal mine has always been a high incidence area of coal spontaneous combustion,which seriously affects the safety and development of coal mine.Therefore,scientific and reasonable warning of coal spontaneous combustion in goaf has attracted more and more attention.Taking the 1034 goaf of Yuandian No.2 Coal Mine as an example,this paper studies the early warning system of coal spontaneous combustion in goaf by means of theoretical analysis,laboratory experiment,expert interview and field measurement,which is of great significance for the prevention and treatment of coal spontaneous combustion in goaf.In this paper,the thermogravimetric experiment and temperature-programmed experiment are used to study the coal samples of No.10 coal seam in Yuandian No.2 Coal Mine.The relationship between the gas released in the oxidation process and the coal temperature is analyzed,and the characteristic temperature range of the coal samples in the oxidation process is determined.The critical temperature of the coal samples in Yuandian No.2 Coal Mine is 70～80℃,and the dry cracking temperature is between120～130℃.The gas index that can be used as dynamic early warning is preliminarily selected as CO,C2H4,C2H6,C3H8,R1（Graham coefficient）,R2（Graham coefficien）,C2H4/C2H6and C3H8/C2H6.Through literature review,expert interview and field research,15 factors affecting coal spontaneous combustion in goaf were analyzed and obtained,and the evaluation system of coal spontaneous combustion in goaf was constructed.The analytic hierarchy process（AHP）was used to calculate the weight of the evaluation index,and the factors affecting the spontaneous combustion of coal in goaf were mainly coal spontaneous combustion tendency,advancing speed of working face and burial depth of coal seam.The risk of coal spontaneous combustion in mined-out area of 1034 working face of Yuandian No.2 Coal Mine was evaluated by AHP and fuzzy comprehensive evaluation model,and the result is k3（general）,which basically agrees with the coal spontaneous combustion situation in the actual mining of coal mine,indicating that the model is reasonable and feasible.By using grey correlation analysis method and combining with underground conditions,the dynamic warning indicators of coal spontaneous combustion in goaf are finally selected as CO,C2H4,C2H4/C2H6,R1,R2.The WOA-ELM neural network dynamic warning model of coal spontaneous combustion was established.The sample data were measured in the field,and the prediction accuracy rate was 95%.Based on the theory of coal spontaneous combustion danger zone division,the coal spontaneous combustion danger zone of 1034 goaf was divided by oxygen concentration,and the maximum width of the spontaneous combustion zone was 69 m.The regional warning model of coal spontaneous combustion in goaf is established.The multi-index early warning method is adopted,the comprehensive early warning model is established,and the emergency measures of different levels are formulated according to different early warning levels,which provides an important basis for the fire prevention and extinguish of goaf.Figure 33 Table 30 Reference 85... |
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